Experimental study of buoyancy-driven ventilation with a single opening between two adjacent building zones

Abstract

In adjacent building zones connected by a single opening, a thermal plume produces a buoyant layer accumulating in the upper space of the experimental zone. The pressure difference between inside and outside the chamber will lead to air flowing in from outside and buoyant fluid flowing out from inside. This study aims to examine the effect of the vertical opening combination on flow regimes in adjacent building zones. The findings indicate that there may be three different flow regimes depending on the relative positions of the opening in the shared wall and the neutral level. The steady flow in two regimes with double stratification formed in the two zones is modeled separately and the theoretical prediction is compared with the experimental results. The flow regime of natural ventilation in the adjacent zones is only related to the height of the outlet, heat source height and effective opening area of the ventilation zones, but not to the buoyancy flux. The interface changes linearly with the height of the heat source at first until the nozzle is immersed in the buoyancy layer, and then the interface height remains constant. The relative size of the openings will also affect the volume flow rate through them, and keeping the areas of the openings along the flow passage equal will maximize the ventilation rate. These research results can provide layout guidelines for building doors and windows and will help designer improve the natural ventilation effect of adjacent building zones.